When an aging water tank needs to be repainted, tank owners have an important decision to make: Should the existing coating be completely removed, or can the tank be successfully over-coated?
In Induron’s latest podcast, Bill Sewell, Induron’s Director of Technical Services, and Joey Thomas, Induron’s Water & Wastewater Business Development Manager, discuss the practical considerations behind repainting aging water tanks—including the value of overcoating existing paint and the continued role of alkyd coating systems.
Two Approaches to Repainting a Water Tank
When it comes time to repaint a tank, there are generally two approaches: full coating removal or overcoating.
Full removal takes an existing coating system all the way back to bare metal. While this approach provides a clean substrate for a new coating system, it can also be expensive and labor-intensive.
Overcoating, on the other hand, involves preparing the existing coating and applying a new coating system over it. When the existing coating is a suitable candidate, this approach can provide a faster and more cost-effective path to extending the tank’s service life.
And in practice, overcoating is the approach most commonly used when repainting aging water tanks.
What Makes a Tank a Good Candidate for Overcoating?
Overcoating isn’t simply a matter of painting over what’s already there.
Before choosing this approach, it’s important to evaluate the existing coating chemistry, the extent of rust and corrosion, and the number of previous paint layers on the tank.
Surface preparation is also critical.
While overcoating doesn’t require the same level of preparation as completely removing the existing coating through abrasive blasting, the surface still needs to be properly prepared. Power washing and hand tool cleaning can help remove contaminants, loose material and corrosion that could otherwise lead to problems such as blistering or premature coating failure.
The goal is to create a sound, clean surface that the new coating can properly adhere to.
Don’t Count Out Alkyd Coatings
The conversation also explores a coating technology that has been protecting water tanks for decades: alkyd paint.
Across rural America, aluminum water tanks can still be found with proven alkyd coating systems that have provided decades of service.
While alkyd coatings may not offer the same level of durability as today’s advanced epoxy or fluoropolymer systems, that doesn’t make them obsolete. For the right application, alkyd coatings remain a viable and cost-effective technology for tank repainting.
Their long history of service is a testament to the value of selecting a coating system that makes sense for the application, environment and budget.
The Value of Overcoating
For many tank owners, the conversation ultimately comes down to one thing: value. Water tank rehabilitation can involve significant costs, and owners may also face challenges related to taking a tank out of service or maintaining water storage capacity during a project.
When the existing coating is suitable for overcoating, avoiding unnecessary full removal can help reduce project costs and get the tank back into service more quickly. More importantly, overcoating can help extend the service life of an existing asset at a lower cost per year of protection. For tank owners working within budget constraints, that can make overcoating a compelling strategy.
The Right Approach Depends on the Tank
All in all, there isn’t a single repainting strategy that works for every water tank. The condition of the existing coating, coating chemistry, corrosion, previous coating layers and required surface preparation all play a role in determining the right approach.
But when an existing coating system is a good candidate, overcoating can provide a practical way to extend a tank’s service life without the cost and labor associated with taking the entire coating system back to bare metal.
Want to learn more?
Listen to the latest Induron podcast with Bill Sewell and Joey Thomas for a deeper conversation about alkyd coatings, overcoating and cost-effective approaches to repainting aging water tanks.